When harvesting plants which are cultivated agriculturally, in many cases it is useful to obtain detailed information about the constituents and other properties of the plants. It has been proposed, therefore, to arrange a suitable measuring device in the vicinity of the crop stream, which irradiates said crop stream with broadband light in the visible wave range or in the near infrared range and identifies the constituents using the spectra of the reflected light. In combine harvesters, the measuring device may be arranged on the grain tank filling worm and may directly cooperate with the conveyed grain flow (e.g., U.S. Pat. No. 6,100,526) or a portion of the grain flow is diverted and guided into a measuring chamber, with which the measuring device is associated (e.g., U.S. Pat. No. 5,751,421). In forage harvesters, the measuring device is generally attached to the discharge device for the chopped crops (e.g., DE 199 22 867 A). In a forage harvester, it has also been proposed to divert a proportion of the chopped crop stream and to guide it past a measuring device by means of a conveyor device (e.g., DE 102 36 515 C and U.S. Pat. No. 5,991,025).
The sample is generally chopped before laboratory analysis of the fodder, carried out by near infrared measuring devices (DE 32 49 175 T).
A potential drawback in certain existing measuring devices is that with larger crop particles and/or cut lengths, the greatest proportion of the measured values is obtained on uncut, and often even on soiled, surfaces of the material so that no meaningful information is obtained about the constituents. Moreover, with larger crop particles or cut lengths, voids may be formed in the samples which also result in unusable spectra and measured values, or a less representative material stream is taken as large particles do not enter the sampling device. Moreover, with large crop particles, the risk increases of blocking the sampling device.